The Application And Research Of Flash File System Based On Real-Time System

In the past, the embedded system mainly applied to the control field, the requirements of data storage are not very high. But with the continuous development of information technology, embedded technology has been widely used in many fields, data which need to store is growing, and the requirement for data storage and management is growing too. Therefore, the research and development of the embedded file system has the important practical significance.Embedded devices are demanding in volume, power consumption, shockproof. Flash memory has a lot of advantages, such as small size, storage capacity, low energy consumption, high performance-to-price and so on. Compared to traditional storage media, Flash memory is more suitable for data storage in embedded systems, and has become one of the storage medium is widely used in embedded systems. At present, there are already a lot of embedded file system for flash memory. But there are still many deficiencies of NAND Flash-based embedded file system, including start-up time, memory consumption, wear leveling, and so on.In this paper, for the shortcomings of current NAND Flash embedded file system, the optimized methods are put forward. In the existing NAND Flash file system (such as the YAFFS), a block both store the file attribute information and file data, the system must be scanned all of the Flash block when startup. This paper will change the file storage format, and management practices, file attributes and file data are stored in different erase blocks, when the system startup, it only scans the blocks which store file attribute, thus reduce start loading time. For memory consumption, the reason is a lot of system control information is stored in memory. Learning from the locality principle, only the information of recently accessed files is stay in memory, and reducing the memory usage of the file system. For wear leveling, data will be divided into two types, cold data and hot data. They are alternately stored in different types of free block, to achieve the purpose of the erase block wear leveling. According to the above method, in the research on the basis of YAFFS file system, design a new file system NFFS. In the test, NFFS achieve the desired goals in functionality and performance. Finally the file system applied in a practical project "food safety tracing system", Almost meet the requirements of the project. But for the practical application, it requires continuous improvement of the system design, and constantly perfects the functionality and improves system stability and robustness.